Nd_2Fe_(14)B/α-Feナノコンポジット薄膜磁石の界面と交換結合

摘要

Nanocomposite thin film magnets with MgO(001)[100]//α- Fe(100)[110]//Nd_2Fe_(14)B(001)[110] and Nd_2Fe_(14)B(100)[001]//α- Fe(110)[110] model interfaces were fabricated by using a thin- films technique with MgO(001) and the Nd_2Fe_(14)B(100) single crystal substrates in an ultra-high vacuum (UHV) atmosphere, respectively. To determine the exchange-coupling constant J_(ex) between the Nd_2Fe_(14)B and α-Fe phases, the resonance field H_r of the ferromagnetic resonance (FMR) spectra and magnetization switching field H_(sf) of magneto-optic Kerr effect (MOKE) curves were measured. The signs of the J_(ex) of the Nd_2Fe_(14)B(001)/ α-Fe(100) and Nd_2Fe_(14)B(100)/α-Fe(110) interfaces were 6.5 and -0.65 erg/cm~2 following first principal calculation. To realize a high maximum energy product (BH)_(max) in anisotropic nanocomposite magnets, a negative J_(ex) interface should be avoided by controlling the nanostructure.